Toners for developing electrostatic images and production method thereof

Abstract

A toner for developing electrostatic images includes a binder, a colorant, iron, silicon, and sulfur. The colorant includes a phosphor and a non-fluorescent colorant. The phosphor includes either one or both of a nitride and an oxynitride each including an alkaline-earth metal, silicon, and an activator element. A volume average particle diameter of the phosphor is greater than or equal to about 50 nm and less than or equal to about 400 nm. An internal quantum efficiency of the phosphor at an excitation wavelength of 450 nm is greater than or equal to about 60%.

What is claimed is: 
     
       1. A toner for developing electrostatic images, the toner comprising:
 a binder; 
 a colorant; 
 iron; 
 silicon; and 
 sulfur; 
 wherein an amount of the iron is greater than or equal to 1.0×10 3  ppm and less than or equal to 1.0×10 4  ppm; 
 an amount of the silicon is greater than or equal to 1.0×10 3  ppm and less than or equal to 5.0×10 4  ppm; 
 an amount of the sulfur is greater than or equal to 500 ppm and less than or equal to 3000 ppm; 
 an amount of the colorant is greater than or equal to 3.5 wt % and less than or equal to 7 wt % based on a total weight of the toner; 
 the colorant comprises a phosphor and a non-fluorescent colorant; 
 an amount of the phosphor is greater than or equal to 0.25 wt % and less than or equal to 4.55 wt % based on the total weight of the toner; 
 the phosphor comprises either one or both of a nitride and an oxynitride each comprising an alkaline-earth metal, silicon, and an activator element comprising any one or any combination of any two or more of europium (Eu), cerium (Ce), manganese (Mn), praseodymium (Pr), neodymium (Nd), samarium (Sm), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), and ytterbium (Yb); 
 a volume average particle diameter of the phosphor is greater than or equal to 50 nm and less than or equal to 400 nm; and 
 an internal quantum efficiency of the phosphor at an excitation wavelength of 450 nm is greater than or equal to 60%. 
 
     
     
       2. The toner of  claim 1 , wherein the phosphor comprises an oxynitride having a general chemical formula represented by MSi 2 O 2 N 2 ;
 the oxynitride has a crystal structure that is the same as a crystal structure of SrSi 2 O 2 N 2 ; 
 the M comprises the alkaline-earth metal and the activator element; 
 the alkaline-earth metal comprises Sr and optionally either one or both of Ca and Ba; 
 the activator element comprises Eu and optionally Ce; 
 the amount of the Sr is greater than or equal to 15 mol % and less than or equal to 99 mol % based on a total amount of the M; 
 the amount of the activator element is greater than or equal to 1 mol % and less than or equal to 20 mol % based on the total amount of the M; and 
 the phosphor has a light emitting peak wavelength in a range of greater than or equal to 530 nm and less than or equal to 570 nm. 
 
     
     
       3. The toner of  claim 1 , wherein the toner has a solid particle, and comprises a coating layer consisting of the binder on its outer surface. 
     
     
       4. The toner of  claim 3 , wherein the coating layer has a thickness of greater than or equal to 0.2 μm and less than or equal to 1.0 μm. 
     
     
       5. The toner of  claim 1 , wherein the toner has a volume average particle diameter of greater than or equal to 3 μm and less than or equal to 9 μm. 
     
     
       6. The toner of  claim 1 , wherein a coefficient of variation of a particle diameter of the toner is greater than or equal to 15% and less than or equal to 25%. 
     
     
       7. The toner of  claim 1 , wherein the toner has a weight average molecular weight of greater than or equal to 7000 and less than or equal to 50000. 
     
     
       8. The toner of  claim 1 , wherein a ratio of a weight average molecular weight to a number average molecular weight of the toner is greater than or equal to 7.0 and less than or equal to 17.0. 
     
     
       9. The toner of  claim 1 , wherein a glass transition temperature of the toner is greater than or equal to 50° C. and less than or equal to 70° C. 
     
     
       10. The toner of  claim 1 , wherein an acid value of the toner is greater than or equal to 5 mg KOH/g and less than or equal to 25 mg KOH/g. 
     
     
       11. The toner of  claim 1 , wherein the binder comprises an amorphous polyester-based resin and a crystalline polyester resin. 
     
     
       12. The toner of  claim 1 , wherein the binder comprises any one or any combination of any two or more of an amorphous styrene polymer, an amorphous acrylic polymer, and an amorphous styrene-acryl copolymer. 
     
     
       13. The toner of  claim 1 , wherein the non-fluorescent colorant comprises either one or both of a dye and a pigment. 
     
     
       14. A method of producing a toner for developing electrostatic images of  claim 1 , the method comprising:
 forming a latex of a binder; 
 forming a first dispersion of the phosphor; 
 forming a second dispersion of the non-fluorescent colorant; 
 mixing the latex, the first dispersion, and the second dispersion to form a mixed solution; and 
 adding an agglomerating agent to the mixed solution to form a primary agglomeration particle comprising the binder, the phosphor, and the non-fluorescent colorant. 
 
     
     
       15. The method of  claim 14 , further comprising disposing a coating layer consisting of the binder on the surface of the primary agglomeration particle to form a coated agglomeration particle. 
     
     
       16. The method of  claim 15 , wherein the binder comprises an amorphous binder; and
 the method further comprises heating a dispersion comprising the coated agglomeration particle at a higher temperature than a glass transition temperature of the amorphous binder to fuse particles in the coated agglomeration particle. 
 
     
     
       17. The method of  claim 14 , wherein the first dispersion and the second dispersion each comprise an anionic surfactant. 
     
     
       18. The method of  claim 14 , wherein the agglomerating agent comprises the iron and the silicon. 
     
     
       19. The method of  claim 14 , wherein a volume average particle diameter of the primary agglomeration particle is greater than or equal to 2.5 μm and less than or equal to 8.5 μm. 
     
     
       20. A toner for developing electrostatic images, the toner comprising:
 a binder; 
 a colorant; 
 iron; 
 silicon; and 
 sulfur; 
 wherein the colorant comprises a phosphor and a non-fluorescent colorant; 
 the phosphor comprises either one or both of a nitride and an oxynitride each comprising an alkaline-earth metal, silicon, and an activator element comprising any one or any combination of any two or more of europium (Eu), cerium (Ce), manganese (Mn), praseodymium (Pr), neodymium (Nd), samarium (Sm), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), and ytterbium (Yb); 
 a volume average particle diameter of the phosphor is greater than or equal to 50 nm and less than or equal to 400 nm; and 
 an internal quantum efficiency of the phosphor at an excitation wavelength of 450 nm is greater than or equal to 60%. 
 
     
     
       21. The toner of  claim 20 , wherein an amount of the iron is greater than or equal to 1.0×10 3  ppm and less than or equal to 1.0×10 4  ppm;
 an amount of the silicon is greater than or equal to 1.0×10 3  ppm and less than or equal to 5.0×10 4  ppm; and 
 an amount of the sulfur is greater than or equal to 500 ppm and less than or equal to 3000 ppm. 
 
     
     
       22. The toner of  claim 20 , wherein an amount of the colorant comprising the phosphor and the non-fluorescent colorant is greater than or equal to 3.5 wt % and less than or equal to 7 wt % based on a total weight of the toner; and
 an amount of the phosphor is greater than or equal to 0.25 wt % and less than or equal to 4.55 wt % based on the total weight of the toner.